There is an ongoing and predicted long-term shortage of licensed pharmacists. Due to the increasing age of the population and the ever-increasing number of prescription medicines available, the demand for prescription drugs is growing at rate that will far exceed the capacity and numbers of licensed pharmacists. The net impact of this imbalance is that pharmacists are increasingly spending more time doing clerical and administrative tasks such as verifying filled prescriptions and checking data entry done by pharmacy technicians. Since the capacity of any one pharmacist is fixed, the output of a pharmacy has become constrained. Consequently, the labor and total cost per prescription continues to rise. The December 2000 Department of Health and Human Services Report to Congress titled “The Pharmacist Workforce: A Study of the Supply and Demand for Pharmacists”, which is hereby incorporated herein by reference, provides an overview of the above problem.
Due to these increased demands on a pharmacist's time, and the resulting increased reliance on technicians and other non-professional staff to fill prescriptions, there is an increased chance for prescription error. While these errors may take many forms, the likelihood of a dangerous or life threatening “adverse drug event” increases proportionally with the increased chance of prescription fill error. Several studies have shown that prescription error rates are consistently in the 2% to 7% range, with a 4% error rate often cited as a reliable average. The number of deaths due to medication errors is estimated to exceed 7,000 per year in the United States alone. Of course, this number does not include non-fatal conditions from drugs that also result in some form of trauma or injury. The resulting litigation costs associated with these prescription fill errors have also dramatically increased.
Many existing pharmacy filling systems and procedures still require a human operator, whether that operator is a technician or a licensed pharmacist, to validate visually whether the drug that is delivered to the customer is correct. Thus, the human factor can contribute to the majority of prescription fill errors. Existing visual verification techniques rely on comparing an electronic image of the prescribed medication, i.e., a picture of the prescribed medication retrieved from a data library, with the actual medication that is dispensed for the patient. Other systems and procedures rely on comparing the dispensed medication with that in the original manufacturer's supply container, or comparing an electronic image of the filled prescription with an electronic image of the prescribed medication retrieved from a data library.
Each of these verification systems present similar problems. First, these known verification methods assume that all drugs are visually distinct. This assumption causes many problems because many drugs are not, in fact, visually distinct and, in other cases, the visual differences between drugs is very subtle. For instance, manufacturers are rapidly exhausting unique shapes, colors and sizes for their solid dosage form products. To further complicate the problem, generic drug manufactures may be using shapes, colors, and sizes that are different than that of the original manufacturer. Second, even though some known systems may utilize a National Drug Code (NDC) bar code to verify that the supply bottle being accessed corresponds correctly to the patient's prescription, a fraction of filled prescriptions that are never picked up are returned to the supply shelves for reuse in later prescriptions. These reused bottles will not, therefore, have a manufacturer's bar code on them. It is, therefore, difficult, if not impossible, to incorporate such validation schemes for these unused prescriptions. Furthermore, in these circumstances, a supply bottle is not available for a visual comparison with the filled prescription. Finally, each of these known manual verification and validation techniques typically requires that the pharmacist spend a significant portion of his day performing these administrative or clerical tasks and allows less time for patient consultation and other professional pharmacist activities.
Many solid dosage pills tend to have visually distinct features. As described in U.S. Pat. No. 6,535,637 to Wootton, the disclosure of which is hereby incorporated herein by reference, one vision-based system takes an image of the dispensed pills and processes the image to obtain a set of characteristic features of the pill. These features may include the coloration, shape, size, and any surface features of the pills. These features are then automatically compared with those of all the pills which can be dispensed by a dispensing apparatus. If a pill can be uniquely identified as the correct pill, the container of pills is accepted. Otherwise, the container is rejected. If, as a result of the processing, a determination cannot be made, the container is provisionally rejected and is subsequently inspected by a pharmacist to determine if the prescription is correctly filled.
Because in many pharmacies throughput of prescriptions is important, it may be desirable to increase the speed of analysis. This may be possible by analyzing a filled, capped container rather than an uncapped container such as that disclosed in Wootton. However, many pharmaceutical containers are transparent with an amber color. The amber coloration of the vial can tint the pills in the vial when an image is taken through the wall of the vial, thereby providing an inaccurate color for the image. Also, because multiple types of vials are used in pharmaceutical dispensing, the degree of amber coloration may differ from vial to vial. Further, in some instances different colors of vials (e.g., red, green, blue) may be used. It may be desirable to address some of these issues to provide a vision-based discrimination system that can operate on a filled, capped vial.